<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <script>
      const obj = {
        age: 100,
        desc: "hello",
        title: "hi",
        toString() {
          // string
          return this.desc;
        },
        // valueOf() {
        //   // number default
        //   return this.age;
        // },
      };
      console.log(Number(obj));
      console.log(String(obj));
      console.log(obj - 100);
      console.log(obj + "jack");
    </script>
  </body>
</html>
